I think (?) that the suggested number of fasting hours is 12. Presumably that means if a family regularly eats dinner at 8 or 9 pm, they could easily still get their 'fasting 12' by not eating an early breakfast. (In my experience, I'm not hungry early anyway if I eat dinner late at night.) The stuff I read on the theory of having a fast every day was about how many hours without food, not what hours.
Fasting can actually be anywhere from 8 to 16 or more. It's typically recommended that you stop eating 3 hours before you go to bed so you aren't going to bed with a full stomach.
I usually stop eating around 6:00-7:00 pm and don't eat again until around 11:00 am - 1:00pm, so my own fasting is usually about 16-19 hrs. I try to keep my food intake between the hours of 9:00 am and 7:00 pm. I do it because of issues with acid reflux and can't go to bed with undigested food in my stomach, but it's better for everyone to stop eating for a while before bed.
We can actually lose weight while we sleep, but it's hard to do when we're busy digesting food.
Some of this will depend on your stomach issues. If you have reflux, you don't want to lie down for a couple of hours after eating. But fasting also allows digestive juices to sit around in your digestive system with no food to work on for longer periods of time. But again, if you look at how people have lived for most of human history as we know it, they ate in the afternoon and then went right to sleep for awhile, then got up and stayed up fairly late, much later than most people think. I think a lot of life is just what you get used to.